Circuit interrupter



Feb. 22, 1949. G. J. EASLEY CIRCUIT NTERRUPTER 2 Sheets-Sheet 1 FiledOct. 30, 1946 Feb. 22, 1949. v G. 'Jl EASLEY 2,432,733

CIRCUIT INTERRUPTER Filed Oct. 30, 1 946 2 Sheets-Sheet 2 WITNESSES:INVENTOR Patented Feb. 22, 1949 UNITED STATES PATENT OFFICE CIRCUITINTERRUPTER Gilbert J. Easley, Forest Hills, Pa., assignor toWestinghouse Electric Corporation, East Pittsburgh, Pa., a corporationof Pennsylvania Application October 30, 1946, Serial No. 706,733

(Cl. D-150) 10 Claims. l

This invention relates to circuit interrupters, in general, and moreparticularly to arc-extinguishing structures therefor.

A general object of my invention is to provide an improved circuitinterrupter of the type drawing both a pressure-generating arc and aninterrupting arc in which contact parting is more quickly attained toobtain a high speed type of interrupter.

A more specific object of my invention is to provide an improved circuitinterrupter of the foregoing type in which a substantially encloseddashpot is associated with the intermediate contact to obtainpractically simultaneous contact parting without the additionalcomplication and i expense of including a side operating rod.

This invention is an improvement over that disclosed in U. S. Patentapplication, Serial No. 465,244, led November l1, 1942, now U. S. Patent2,406,469, issued August 27, 1946, by Leon R. Ludwig, Winthrop M. Leeds,and Benjamin P. Baker, and assigned to the assignee of the instantapplication, and in which there is disclosed and claimed a high speedtype of circuit interrupter in which a pivotally mountedpressuregenerating contact is moved by a side operating rod relative toa stationary intermediate contact to establish a pressure-generating arcsimultaneously with movement of a lower movable Contact from theintermediate Contact to draw the interrupting arc.

Such a construction, aside from the complication of a side operatingrod, is high speed in action since both the pressure and interruptingarc are simultaneously drawn away from the intermediate contact therequisite arc length.

It is a further object of my invention to obtain the advantages ofsimultaneous break operation obtained in the interrupter described inthe Ludwig et al. patent, while at the same time avoiding the necessityof utilizing the side operating rod for actuating thepressure-generating contact.

Further objects and advantages will readily become apparent upon areading of the following specification taken in conjunction with thedrawings, in which:

Figure 1 is a side elevational view, partly in section, of a circuitinterrupter embodying my invention and shown in the closed circuitposition;

Fig. 2 is an enlarged vertical sectional View, with a portion taken at aquarter section, as shown by the lines II-II of Fig. 3, of the lefthandarc-extinguishing unit of Fig. 1, the contacts being shown in the partlyopen circuit position; and

Fig. 3 is a sectional view taken substantially along the line III-III ofFig. 2 looking in the direction of the arrows.

Referring to the drawings and more particularly to Fig, 1 thereof, thereference numeral I designates a tank in which is disposed a suitablearc-extinguishing fluid 2, in this instance circuit breaker oil, fillingthe tank I to the level 3. Depending from the cover 4 of the tank I aretwo insulating bushings 5, 6 at the lower ends of which are securedrigidly in place identical arcextinguishing units, generally designatedby the reference numeral 'I.

The arc-extinguishing units l are electrically bridged in the closedcircuit position, as shown by the full lines in Fig. 1 by a U-shapedconducting cross-bar 8 reciprocally operated in a vertical direction, asviewed in Fig. 1, by an insulating operating rod S actuated by suitablemechanism, not shown.

Referring more specifically to Fig. 2, which shows enlarged theleft-hand arc-extinguishing unit 'I of Fig. l, it will be observed thatthe terminal stud Ii) extending through the left-hand bushing 5 hasthreadedly secured and clamped to its lower end a top dome casting II.Positioned within the top dome casting II is a pivotally mountedpressure-generating contact I2 biased downwardly by a compression springI3, the latter having its upper seat against an offstanding bracket I4,in this instance forming an integral part of a plate I la secured bybolts Mb to the casting I I. A eXi-ble conductor I5 electricallyconnects the pressure-generating contact I2 to the bracket I4 and henceto the dome casting II so that the pivot pin I6 does not need to carrythe breaker current in the closed circuit position thereof.

Preferably, an over-pressure relief valve I'I is provided to permit therelief of excessive pressure formed within the pressure-generatingchamber, generally designated by the reference numeral I8 and defined bythe wall portions of the dome casting II. Also, a gas relie-f valve I isprovided which closes during the interrupting operation and opensfollowing the completion of the interrupting operation to permitaccumulated gas to pass upwardly out of the pressure-generating chamberI8 and hence out of the arc-extinguishing unit l.

Secured to the lower end of the dome casting I I by insulating tie rods2li are a plurality of suitably configured insulating plates formingfluid flow ally passages of the type set forth in the aforesaid Patent2,406,469. The passage structure is fully set forth in the aforesaidpatent to which reference may be had for the configuration of theseveral plates. For the purpose of understanding my invention, it ismerely necessary to note that the insulating plates collectively alignto form two Vertical new passages, generally designated by the referencenumeral 2 l, and more clearly shown by the sectional view o1- Fig. 3.The two vertical now passages El permit communication between thepressure-generating chamber i3 and the interrupting chamber, generallydesignated by the reference numeral 22. The lower ends of the-twovertical new passages have communicating therewith pairs of inletpassages 23 which permit fluid under pressure from thepressure-generating are to ilow to radially inwardly toward theinterrupting arc 2li established between the intermediate contact 25 andthe lower movable contact 2li, which forms the upstanding portion of thecross-bar 8. The pressure-generating arc 2? is established between thepressure-generating contact l2 and the upper portion of the intermediatecontact 25.

The oil under pressure formed by the establishment of thepressure-generating arc 2 Vows downwardly, as indicated by the arrowsand radiinwardly through the inlet passages 23 toward the interruptingarc 24 to pass through orices 23 and outwardly from thearc-extinguishing unit 'ithrough a plurality of venting passages '29.The venting passages 25 pass out of the unit 'l in opposite directionsin a direction perpendicular to the plane of the drawing of Fig. 2 andare `shown more clearly in Fig. 3.

31 formed therein which closely surrounds the upper portion of theintermediate contact 25.

Preferably, the region 3S below the iiange or ring 33 communicates withthe region exterior of the arc-extinguishing unit l by means of a bretube 39 having an adjusting screw @dat its outer end which acts as avalve to vary the size of the exhaust passage through vthe tube. One maycause the removal of the screw 34 from the ring 33 and intermediatecontact' by inserting the end of a screw-driver through the fibre tube39. When the screw Bil is removed from'the ring 33 and also theintermediate contact 25, the intermediate contact 25 may be removedvertically upwardly or downwardly for repair or replacement. Since thereis relatively little wear on the flange 33, there is no need for thelatters replacement.

The operation of the interrupter will now be explained. In the closedcircuit position of the interruptor, as shown by the full lines in Fig.l, the electrical circuit therethrough includes terminal stud i9, topdome casting H, Ibracket I4, flexible conductor l5, rotatablepressure-generating Contact l2, intermediate contact 25, lower movableContact 2S through the cross-bar B and through the right-handarc-extinguishing unit'in an identical manner to the other terminal ofthe interrupter. To effect the opening operation of the interrupter,suitable mechanism, not shown but which is responsive to manualoperation or to overload currents carried by the interrupter causesdownward movement of the insulating operating rod 9. lThe downwardmovement of the operating rod 9 causes downward movement oi bothlowermovable contacts 26.

Because of the provision of the compression springs i3, the threecontacts, l2, 25 and 25 will initially move downwardly together makingcontacting engagement. However, the pressuregenerating contact l2 will,after a predetermined clockwise rotation, strike the stop screw 82a andbe halted thereby. Further downward travel oi the contacts 25 and 26will cause the establishment of a lpressure-generating arc 2l within thepressure-generating chamber i8, the provision of the bypassing means 32permitting the intermediate contact 25 to maintain contactingengagementwithlower contact 2li during this time.

The downward movement of the intermediate contact 25 and the lowermovable Contact 26 continues with the two making contacting engagementuntil the flange or ring 33 secured to the intermediate Contact 25passes the lower ends of the grooves 32 provided in the insulating guidecylinder 3|. When this occurs, the dashpot 3&3 will be effective tocause halting downward movement of the intermediate contact 25 tothereby cause a separation to take place between the intermediatecontact 25 and the lower movable contact 2li to establish aninterrupting arc V2li within Ithe interrupting chamber 2i? of the unit1t will consequently be noted that when the flange 33 passes the lowerends of the groove 132, the dashpot Sii will thereafter Cause thentermediate Contact 25 to move downwardly at a slower speed than thespeed of the lower movable contact 26. This draws the interrupting arc2li in the interrupting chamber 22 which will be extinguished by the uidflow from the pressure-generating arc l. It will be observed thatfollowing `the time oi eiective operation of the dashpot Sil, that is,when the by-passing-means Vbecomes ineiicective, thereafter both thepressuregenerating and interrupting arcs 2i, E@ continue to lengthen tothe requisite arc length in a manner simulating that of the aforesaidPatent 2,406,469.

It will be noted that a distinct advantage oi my invention is thesubstantially enclosed construction oi the dashpot 3Q. Thus, pressurewithin the pressure-generating chamber I8 is not permitted to act uponthe top or rear side of the piston 33, asit moves downwardly during itsopening stroke. If there were unication between the top or rear side ofthe piston and the pressure-generating chamber I8, during theYinterruption of high values of current, the separation between theintermediate contact 25 and the lower movable contact 2d would bedelayed inasmuch as the pressure would assist the compression spring 35in driving the piston 33 and intermediate contact 25 downwardly morerapidly than would be the case in interrupting low values of current.However, during the interruption of high values of current the length ofthe pressure-generating arc need not be so long as during theinterruption oi low values of current. Consequently, it is not desirableto delay opening of the interrupting contacts during the interruption ohigh values oi current which would result should lthere be communicationbetween the rear side of the piston 33 and the pressuregeneratingchamber i8, Also the downward speed of the intermediate contact issubstantially independent of the pressure acting on the upper end of theintermediate contact for two reasons: lst, the pressure on the upper endis partly counterbalanced by the pressure on the lower end of theintermediate contact; 2d, it is characteristic of dashpot action, withfluid bleeding out oi an orifice of Xed size, to have a rate of fluidescapement substantially independent of driving force on the piston.

It will be also observed that the adjustment of the uid adjusting screw40 will determine the rate of escape of oil from the region 38 in frontof the piston 33 during its opening movement. Thus, the downward speedof the intermediate contact 25, as it moves within the 0peratingcylinder 3l, may be regulated., Also, the by-pass means 32 permits theda-shpot 3@ to be ineffective duringthe initial portion of the downwardtravel of the intermediate contact 25 and piston 33.

The further advantage results from my invention that the number ofoperating parts is reduced as compared with a construction involving aside operating rod as set forth in the aforesaid Patent 2,406,469. Thus,by the arrangement which I have provided, the number of operative partsis practically the same as the case where one has a two-break type ofinterruptor, the breaks occurring sequentially. Although strictlyspeaking the two breaks in my improved interruptor occur in a sequentialmanner, the provision of the dashpot causes the two breaks to occuralmost simultaneously, and more rapidly than the ordinary sequentialbreak type of interrupter. Also, the insulation conditions are notimpaired by the utilization of my invention since no metallic partsparallel any of the are gaps.

From the foregoing description, it will be apparent that I have providedan improved circuit interruptor of the two-break type in which by theuse or" my invention the breaks occur practically simultaneously. Also,it will be noted that in the operation oi my invention, the interruptingarc 2d is drawn earlier than in the conventional consecutive partarrangement. This results by virtue of the by-passing means 32 whichequalizes the pressure on both sides of the piston 33 to render thedashpot 30 ineffective during the initial portion of the opening stroke.

During the closing stroke, the movable contact 535 moves upwardly topick up the intermediate contact 25 and raise the latter charging thecompression spring 35 until the intermediate contact 25 makes engagementwith the relatively stationary pressure-generating contact I2, thecompression spring I3 providing the requisite contact pressure.

Although I have shown and described a specic structure, it is to beclearly understood that the same was merely for the purpose ofillustration and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of the appended claims.

I claim as my invention:

l.. In a circuit interrupter, a relatively stationary contact, anintermediate contact cooperable with the relatively stationary contactto establish an arc, a movable contact separable from the intermediatecontact to establish a second serially related arc, a piston secured toand movable with the intermediate contact, an operating cylinder withinwhich the piston moves, by-passing means associated with the operatingcylinder to equalize the pressure on both sides of the piston onlyduring the initial portion of the opening travel of the piston, andmeans preventing the arcing pressure from acting upon the piston toaccelerate its opening movement.

2. In a circuit interrupter, a relatively stationary contact, anintermediate contact cooperable with the relatively stationary Contactto establish a pressure-generating arc, an enclosed dashpot protectedfrom the arcing pressure associated with the intermediate contact todelay the opening movement oi the latter, a movable contact separablefrom the intermediate contact to establish an interrupting arc, andmeans rendering the dashpot ineiective during the initial portion of theopening operation.

3. In a circuit interrupter, a relatively stationary Contact, anintermediate contact cooperable with the relatively stationary contactto establish an arc, a movable contact separable from the intermediatecontact to establish a second serially related arc, a piston secured toand movable with the intermediate contact, an operating cylinder withinwhich the piston and at least a portion of the intermediate contactmove, a longitudinally extending groove disposed on the inner wall ofthe operating cylinder to equalize the pressure on both sides of thepiston only during the initial portion of the opening travel of thepiston, and means preventing the arcing pressure from acting upon thepiston to accelerate its opening movement.

4. In a circuit interruptor, a relatively stationary contact, anintermediate contact oooperable with the relatively stationary contactto establish an arc, a movable contact separable from the intermediatecontact to establish a second serially related arc, a piston secured toand movable with the intermediate Contact, an operating cylinder withinwhich the piston moves, a longitudinally extending groove disposed onthe inner wall 0f the operating cylinder to equalize the pressure onboth sides of the piston only during the initial portion of the openingtravel of the piston, and means biasing the piston and intermediatecontact in the opening direction, and means preventing the arcingpressure from acting upon the piston to accelerate its opening movement.

5. In a circuit interruptor of the liquid break type, a pair of contactsseparable to establish an arc, a third contact separable from one of theaforesaid pair of contacts to establish a second serially related arc,means biasing the said one contact in the opening direction, andsubstantially enclosed dashpot means operative substantiallyindependently of the arcing pressure for controlling the `openingmovement of the said one contact.

6. In a circuit interrupter, a relatively stationary Contact, anintermediate contact cooperable with the relatively stationary contactto establish an arc, a movable contact separable from the intermediatecontact to establish a second serially related arc, a substantiallyenclosed dashpot associated with the intermediate contact to control thelatters opening movement, and means rendering the dashpot ineffectiveduring the initial portion of the opening operation.

7. In a circuit interruptor, a relatively stationary contact, anintermediate Contact separable from the stationary contact to establisharcing, a movable contact separable from the intermediate contact toestablish arcing, a substantially El enclosed dasli-pot--4 isolated.from the-1V areing4 pressure-:associated With the inter-mediatecontactto regulate theopening movement; thereof, and fluid regulatingmeans for determining the timeof actuation of the dashpot.

8. A circuitinterrupter including an arc extingushingunit submerged inliquid, a relatively stationary Contact, an intermediate contactcocperablevv'ith the relatively stationary contact to establish an arc,a movable Contact separable from the intermediate Contact to establish asecondA serially related arc, a piston secured to and movable: with theintermedia-te Contact, an operating4 cylinder Within which the pistonmoves, and'means venting the forward side of the pistn vtothe regionexteriorly of the unit.

9. A circuit interrupter of `the liquid-break type includingan arcextinguishing unit submerged in the liquid, a relatively stationaryContact, an intermediate contact cooperable with therelatiVelyfsta'tiona-ry contact Ito establish a pressuregenerating arc,an enclosed dashpot protected `from the arclngl pressure associatedwlth'the intermediate Contact to delay the opening movement of thelatter, a movable contact separable fromthe intermediate contact toestablish an interruptingA arc, and means venting the dashpot totheregion exteriorly of the unit.

8 10. Al circuit interrupter of the liquid-break type-incl udng an areextinguishing unit submerged-in the-liquid, a relatively stationarycon-` REFERENCES CITED The following references are of record in theleoi this patent:

UNITED STATES PATENTS Number Name Date 1,872,530 Turnpenny Aug. 16, 19321,949,258- Paul Feb. 27, 1934 2,156,388" Grosse May 2, 1939 2,158,846Balachowsky May 16, 1939 2,406,469, Ludwig et al. Aug. 27, 19462,412,858 Baker et a1. Dec. 17, 1946

